Why is the death of Julius Caesar significant?

Julius Caesar was assassinated by about 40 Roman senators on the "ides of March" (March 15) 44 BCE. Caesar's death resulted in a long series of civil wars that ended in the death of the Roman Republic and the birth of the Roman Empire.

less available tax revenue

this basically means that when they get money from taxes wirth having a lower gdp they get less then what others have with a higher gdp